이 논문에서는 교량받침 교체를 위한 에폭시 주입 공법을 제시하였다. 에폭시 주입 공법의 성능 평가를 위하여, 에 폭시 주입성 실험 및 통공앵커의 인발실험을 수행하였다. 에폭시 주입성 실험은 빈 공간을 갖고 있는 콘크리트 블록 내에 통공 앵커를 이용하여 에폭시를 주입하고, 콘크리트 블록을 절단한 후, 주입성능을 육안으로 관찰하였다. 또한, 인발실험은 2가지 형태의 통공앵커를 콘크리트 블록 내에 삽입하여 수행하였으며, 2가지 형태의 통공앵커에 대한 인발실험 결과를 비교하고, 케 미컬 앵커의 인발강도와도 비교하였다. 실험 결과 통공앵커는 교량받침 교체공사를 위한 에폭시 주입성과 인발성능이 우수한 것으로 나타났다.

Gases such as hydrogen can generate from the disposal canister in high-level radioactive waste disposal systems owing to the corrosion of cooper container in anoxic conditions. The gas can be accumulated in the voids of bentonite buffer around the disposal canister if gas generation rates become larger than the gas diffusion rate of bentonite buffer with the low-permeability. Continuous gas accumulations result in the increase in gas pressure, causing sudden dilation flow of gases with the gas pressure exceeding the gas breakthrough pressure. Given that the gas dilation flow can cause radionuclide leakage out of the engineered barrier system, it is necessary to consider possible damages affected by the radionuclide leakage and to properly understand the complicated behaviors of gas flow in the bentonite buffer with low permeability. In this study, the coupled hydro-mechanical model combined with the damage model that considers two-phase fluid flow and changes in hydraulic properties affected by mechanical deformations is applied to numerical simulations of 1-D gas injection test on saturated bentonite samples (refer to DECOVALEX-2019 Task A Stage 1A). To simulate the mechanical behavior of microcracks which occur due to the dilation flow caused by increase in gas pressure, a concept of elastic damage constitutive law is considered in the coupled hydro-mechanical model. When the TOUGH-FLAC coupling-based model proposed in this study is applied, changes in hydraulic properties affected by mechanical deformations combined with the mechanical damage are appropriately considered, and changes in gas injection pressure, pore pressures at radial filters and outlet, and stress recorded during the gas injection test are accurately simulated.

This paper analyzed the correlation between injection molding factors through correlation analysis. In addition, the decision-tree model, which is a white box model with excellent explanatory power, was used to obtain optimal molding conditions that satisfy multiple constraint conditions. First, 243 data to be used in the experiment were created through a full factorial design. Second, a correlation analysis was conducted to understand the correlation. Third, to verify the decision-tree model, the prediction performance was evaluated using RMSE. As a result, good prediction performance was confirmed. A decision-tree experiment analysis was conducted. As a result of the progress, the same results as the correlation analysis were derived. Based on the previous analysis results, optimal molding conditions were applied to CAE. As a result, the amount of deformation in the multi-cavity could be improved by about 1.1% and 2.72% while satisfying the constraint.

This study is to investigate the effect of material for GPF on the PM reduction characteristics before the improvement of filter efficiency in GPF. The material of GPF was changed to ceramic and metal. The ceramic material was applied to SiC, and the metal materials were employed to STS 310s, STS 316s, and STS 410s. The number of honeycomb and wall thickness were set to 200CPSI, 0.3987mm, respectively. The inlet mass flow was fixed at 0.00695kg/s. The inlet air temperature was changed from 500K(0s∼350s) to 1000K(400s∼900s). It was found that the differences in loading amount according to the GPF materials were difficult to observe because the pore density and porosity were set to be the same to affect only the mechanical properties. STS 310s with the highest temperature value had the fastest regeneration time. However, as time goes on, SiC had the highest regeneration rate characteristics. The reason is that the high-temperature region in the GPF by the high-temperature exhaust gas was rapidly transferred toward the outlet due to the high thermal conductivity of SiC.

This study compared the immune responses, stress relief and weight gains of needle or needle-free intramuscular and needle-free intradermal vaccination in pigs. When the same amount of a foot-and-mouth disease (FMD) vaccine was administered to pigs, antibody titers at 4 weeks after the 1st and 2nd FMD vaccination were not significantly different between the needle (IM-S) and needle-free (NM-P250) intramuscularly vaccinated groups, but the weight gain of NM-P250 was significantly increased compared to that of IM-S at 8 weeks after the 2nd FMD vaccination (p<0.05). In addition, serum cortisol concentrations of NM-P250 were considerably decreased compared to those of IM-S on the 5th and 7th day after the 1st and 2nd FMD vaccination (p<0.05). However, the antibody titers of IM-S vaccinated with 2 mL of FMD vaccine were significantly increased compared to those of the needle-free intradermal vaccinated group with 0.5 mL of FMD vaccine at 4 weeks after the 1st and 2nd FMD vaccination (p<0.05). In conclusion, the needle-free intramuscular injection for the FMD vaccination can be chosen for weight gain and stress relief in pigs.

Laser cladding a surface treatment process that grants superior characteristics such as toughness, hardness, and corrosion resistance to the surface, and rebuilds cracked molds; as such, it can be a strong tool to prolong service life of mold steel. Furthermore, compared with the other similar coating processes – thermal spray, etc., laser cladding provides superior bonding strength and precision coating on a local area. In this study, surface characteristics are studied after laser cladding of low carbon steel using 18%Cr-2.5%Ni-Fe powder (Rockit404), known for its high hardness and excellent corrosion resistance. A diode laser with wavelength of 900-1070 nm is adopted as laser source under argon atmosphere; electrical power for the laser cladding process is 5, 6, and 10 kW. Fundamental surface characteristics such as crossectional microstructure and hardness profile are observed and measured, and special evaluation, such as a soldering test with molten ALDC12 alloy, is conducted to investigate the corrosion resistance characteristics. As a result of the die-soldering test by immersion of low carbon alloy steel in ALDC12 molten metal, the clad layer's soldering thickness decreases.

The abnormal meat could caused by abscess, fibrosis and granuloma in the region of the neck by the adverse effect of foot-and-mouth disease (FMD) vaccination practice for Korean swine. After FMD vaccination was implemented in 2010, the number of incidences of abnormal meat has been increasing. In this study, it was evaluated whether needless intradermal injection (NII) of FMD vaccine reduces abnormal meat at the injection site in comparison to conventional intramuscular injection (IM). In addition, the onset of humoral immunity was analyzed in order to see if NII of this vaccine is able to mount comparable antibody response with IM. This study was carried out in four Korean pig farms. The O-type FMD vaccine was implemented via NII at three farms and the control group was vaccinated via IM. Antibody titers were compared from the serum samples taken from 10 random pigs at age of 8, 12, 16 and 22~24 weeks of age. The O+A type FMD vaccine was also compared with the same protocol. When test animals were slaughtered, incidence, type and size of abnormal meat were recorded. The results of this study showed that the antibody titers between intradermal and intramuscular group were similar but a significant difference in the incidence of abnormal meat formation was observed between two groups (p < 0.05). In summary, needless intradermal injection of FMD vaccination was proven to be effective for the onset of humoral immunity and reducing abnormal meat formation.

In this study, the effects of fuel injection pressure changed from 45 to 65 MPa on combustion and emission characteristics were investigated in a common rail direct injection (CRDI) diesel engine fueled with diesel and palm oil biodiesel blends. The engine speed and engine load were controlled at constant 1700rpm and 100Nm, respectively. The tested fuel were PBD20 (20 vol.% palm oil biodiesel blended with 80 vol.% diesel fuel). The main and pilot injection timing was fixed at 3.5°CA BTDC and 27°CA BTDC (before top dead center), respectively. The experimental results show that the combustion pressure and heat release rate increased. In addition, the indicated mean effective pressure (IMEP) and maximum combustion pressure increased with an increase of the fuel injection pressure. Hydrocarbon (HC), smoke opacity and carbon monoxide (CO) decreased, but oxides of nitrogen (NOx) emissions increased as fuel injection pressure increased.

This study was conducted for the purpose of suggesting a standard that can be used under ambient temperature by improving the low mechanical and thermal properties of ABS. PC was used as a filler, and post-curing conditions of the ABS/PC blend injection material were investigated. It was found that the ABS/PC blend injection material having a PC content of 20 wt.% or more showed little change in tensile properties at a temperature of 50°C, and a decrease in tensile properties of less than 10% at 80°C.

Ti-Al-Si target and Cr-Si target are sputtered alternately to develop a multi-layered nitride coating on a steel mold to improve die-casting lifetime. Prior to the multi-layer deposition, a CrN layer is developed as a buffer layer on the mold to suppress the diffusion of reactive elements and enhance the cohesive strength of the multi-layer deposition. Approximately 50 nm CrSiN and TiAlSiN layers are deposited layer by layer, and form about three μm-thickness of multi-layered coating. From the observation of the uncoated and coated steel molds after the acceleration experiment of liquid metal injection casting, the uncoated mold is severely eroded by the adhesion of molten metallic glass. On the other hand, the multi-layer coating on the mold prevents element diffusion from the metallic glass and mold erosion during the experiment. The multi-layer structure of the coating transforms the nano-composite structured coating during the acceleration test. Since the nano-composite structure disrupts element diffusion to molten metallic glass, despite microstructure changes, the coating is not eroded by the 1,050 oC molten metallic glass.

In this study, we used a numerical analysis program to study the molding conditions that affect the flow rate at the time of injection, using a spiral mold, which is mainly used for the evaluation of the flow rate of plastic resin. The mold temperature, melt temperature, and flow rate are composed of experimental factors. The three plastic forming factors were divided into five to six levels each. Since then, changes in the flow rate temperature were analyzed as the level of each forming factor increased. Experiments showed that all three forming factors increased the filling length of the spiral mold and the temperature of the flow front by a total of 34.53°C, melt temperatures increased the temperature of the flow front by a total of 34.53°C, the temperature increased by the flow rate was 23.5°C, and the temperature increased by the mold temperature was 1.99°C. It was shown that the melt temperature was the largest, followed by the flow rate and mold temperature. It was also possible to check the effect of plastic forming factors on the speed of the flow front.

When the product is taken out after the injection process, the surface of the product and the mold are attached and to separate them, it is necessary to consider the frictional force between the mold surface and the product surface. Therefore, to reduce the frictional force, a subtraction gradient for the rib shape is generally applied, and a lapping process is performed to improve the surface roughness of the rib shape surface of the processed mold. Therefore, research is needed to improve the surface roughness when processing the rib. In this study, slotting processing was applied to improve surface roughness when processing ribs. Slotting processing is a processing method that removes material through the feed motion of the tool, and processing is possible regardless of the aspect ratio of the processing shape. A slotting tool was developed for rib machining and a comparative experiment with electric discharge machining was performed. Also after processing, the surface roughness and processing time were compared and analyzed, and the improved surface roughness and fast processing time characteristics of the slotting processing compared to electric discharge processing were confirmed.

Recently, the demand for reliability verification is increasing while designing and manufacturing molds using injection molding computer aided engineering(CAE). When performing flow analysis verification, a spiral mold is produced and compared with CAE. Because of the spiral shape, we needed a comparative evaluation with the flow distance of products with different forms. So, we compared the weight and flowed length using CAE. Variables are the change in the width of the spiral shape and the shape of the bar and plate. When the width of the spiral shape is 23mm rather than 15mm, the flow distance flows 30∼70mm more, with a maximum difference of 13%. As a result of comparing the spiral shape and the long square shape with the same width, the spiral shape had a flow distance of 60 to 105mm further, and a difference of up to 28% was found. As a result of comparing the plate shape and the spiral shape with a 15mm width product, the spiral shape has a flow distance of 310∼380mm further, and a difference of up to 82% is different.